[ISSUE?] Sidechain send channel not available

I randomly experience missing side-chain-send-channels. The problem looks like this:

  1. Insert a side-chain-able plug-in into an instrument track
  2. Try to send to the side-chain-channel from another instrument track
  3. No side-chain available.

Problem (or bug?) is shown here for the Steinberg delay plug-in:
http://youtu.be/eCh0VarX4Nw

My Workaround(seems to be working so far, knock on wood):

  1. Insert a side-chain-able plug-in into an audio track
  2. Move it to the instrument track you want it inserted into
  3. Voila: Side-Chain-Send is avaiable.

Unfortunately it is very hard to reproduce this faulty behaviour by creating this setting on purpose within an empty project. It only happens at random in bigger projects. But once the problem occurs in a project I can always reproduce it.
This is very irritating because I always have to be anxious if the problem will befall me again in one of my the next projects.

Does anyone experience the same problem?

Dr. Max